Wireless communication networks, e.g. wireless mesh networks, are composed of multiple, even hundreds or thousands of radio nodes (later referred as “nodes”) that communicate with each other over two or more radio interfaces. To support the various functions of such wireless communication networks, the nodes typically need to operate in different roles. One or more nodes of the network operate in sink role, i.e. they are part of gateways to other networks, e.g. Internet, and deliver data in and from the wireless communication network. The rest of the nodes of the network may be divided into routers and non-routers depending on if they need to participate in data forwarding. Routers maintain the connectivity of the network and forward data of other nodes when needed. Non-routers may transmit their own data and receive data directed for them, but typically they do not route data of other nodes.
The wireless communication network may comprise sensor devices that produce data, which is monitored over the Internet. Each sensor device is equipped with one or more radio interfaces and various sensors and they operate as nodes of the wireless communication network. The radio interface of each node is used to deliver the data towards the sink node or any other node in the network. Even if a single node cannot directly reach the sink node, the network formed between the nodes takes care of routing the data and control messages to the desired destination. A routing protocol implemented in each node chooses the path to the sink(s). Similarly, there may be data that is delivered, over multiple radio links, from the sink node to the node(s) or between the nodes inside the wireless communication network.
The wireless communication networks may need to adapt into different types of environments, device densities, topologies, and arbitrary changes in any of the previous.
According to one prior art solution nodes of a wireless communication network may be divided into active, i.e. relaying, and super-saving roles. A root node generates a routing path through the network, i.e. selects the active nodes, and the active nodes on the path are not allowed to change their roles to super-saving role. The selection is repeated periodically. The method is based on centralized decision making by the root node, which may reduce complexity of the nodes. One drawback of the prior art solution is that it does not address the local availability of the active devices around the mesh network, e.g. in case new terminals would like to join the network (but are in the radio coverage of super-saving terminals only). Additionally, updating all router information from central node can cause extensive signalling especially when number of nodes is high.
According to another prior art solution selection of parent routing nodes in a hierarchical wireless mesh network may be performed by exchanging path metric information. Signal quality (e.g. signal-to-noise ratio and/or received signal strength) may be measured to provide the path metric information and the selections are made based on this information. Hence, in this case there is no real role selection or role is selected individually for each transmission to optimize the route path to increase the efficiency of the routing. However, all nodes need to exchange path metric information and be ready for being part of data path.